1. Field of the Invention
This invention relates to the photoinitiated release of a drug, dye or other material from a surfactant vesicle such as a phospholipid vesicle into a surrounding environment.
More particularly, this invention relates to the photoinitiated solubilit-controlled alteration (e.g., disruption, reorientation or solubilizatin) of a polyelectrolyte surrounding a surfactant vesicle such as a phosphatidylcholine vesicle dispersed in aqueous media. The alteration occurs by means of a polyelectrolyte material which is sensitive to radiation and responsively changes its solubility in the aqueous medium. Such polyelectrolyte materials have a titratable funtional group. A titratable functional group is defined as a group that will accept or release protons such as an acidic titratable functional group or a basic titratable functional group. The titratable material, which may or may not be a polymer, may be dispersed in or soluble in the aqueous medium or it may be anchored on the vesicle wall prior to its vesicle release affecting activity.
2. Background of the Art
Small amounts of materials have previously been provided by means of capsules or microcapsules. Solid, semisolid, oil or liquid materials have been provided in capsule form for such diverse suses as medication, agricultural supplements, imaging, lubrication, fragrances and the like. The capsules or microcapsules have normally been opened by physical forces such as pressure or abrasion as shown in U.S. Pat. Nos. 3,016,308; 3,516,941; 4,201,404; 4,487,801 and 4,606,956. U.S. Pat. No. 3,503,783 discloses microcapsules having coloring material therein which capsules are rupturable by the application of heat, pressure and/or radiation because of a metal coating on the surface of a capsule.